Design And Performance Evaluation Of Three-cylinder Energy Recovery Device For SWRO System

The energy recovery device plays an important role in greatly reducing the energy consumption of the reverse osmosis seawater desalination system(SWRO).The existing double-cylinder valve-controlled energy recovery device(RS-ERD)is likely to cause high and low pressure fluid flow and pressure pulsation problems due to frequent phase switching,which affects the operation stability of the device and the reverse osmosis system.The development of energy recovery devices with better operating continuity and stability is an important technical direction for the development of products of this type.This paper designs and develops a new type of three-cylinder valve-controlled energy recovery device(TC-ERD).By optimizing the pressure exchange status of fluids in different cylinders,orderly switching between the boosting stroke and the relief stroke with instantaneous overlapping function is realized.Improve and enhance the continuity and stability of device operation.The operation performance of the TC-ERD device in the reverse osmosis seawater desalination system was studied.The results showed that at the rated treatment volume of 30m~3/h and the operating pressure of 5.0MPa,the average pressure fluctuation amplitude of the high-pressure fluid and low-pressure fluid were 0.07MPa and 0.03MPa,which is 86%and 40%lower than the two-cylinder RS-ERD device respectively;the flow pulsation amplitude is1.33m~3/h and 0.9m~3/h,which is 65%higher than that of the RS-ERD device,but the low-pressure fluid is reduced by 57%.The paper researches and analyzes the operation performance of the TC-ERD device under the conditions of variable processing capacity of 20m~3/h?35m~3/h.The results show that with the increase of the processing capacity of the device,the pressure pulsation amplitude of the high-pressure fluid basically remains unchanged.Which is 0.07?0.08MPa.The corresponding high-pressure fluid flow pulsation amplitude increases with the increase of the processing volume.When the processing volume is 35m~3/h,the flow pulsation amplitude is 1.64m~3/h,which is an increase of23.30%under the rated flow of 30m~3/h.The pressure and flow pulsation amplitude of the low-pressure fluid increase with the increase of the processing volume,and the corresponding intervals are 0.02?0.08MPa and 0.67?1.14m3/h;the maximum pulsation amplitude of the flow rate increases by 26.67%compared with the rated flow rate.The increase in fluid flow pulsation amplitude is basically the same.The average internal leakage rate of the TC-ERD device is 4.0%to 4.5%,and the energy recovery efficiency of the corresponding device remains above 90%.